The invention relates to a differential gear distributing torque between a forward wheel shaft to be driven and a rear wheel shaft to be driven on a vehicle and particularly relates to maintaining positive drive from the input shaft to each of the output shafts through maintaining axial force transmission.
1. State of the Art
Vehicles with tandem-driven rear axle bogies generally incorporate a differential gear for distributing the drive torque delivered by the engine to the forward and rear wheel shafts. It has been usual for both wheel shafts to be continuously powered. The increasingly common use of air-sprung wheel shafts affords the possibility even in a tandem bogie of raising one of the wheel shafts, normally the rear one, which thereby comes off load but continues to rotate. This also eliminates the force via the differential which provides guidance of the input shaft, consequently impairing not only gear engagement in the transfer gearbox but also the differential locking function, and causing undesirable wear. These problems arise from the occurrence of axial play in the differential gear, with the result that the now off-load input shaft is no longer guided as well as previously. These problems do not occur when the rear wheel shaft is lowered and the input shaft is subjected to normal torque load.
2. Object of the Invention
The object of the invention is to provide a differential gear which eliminates the problem of uncentered drive and inferior functioning of the differential lock in a tandem bogie when the rear wheel shaft is raised and off load.
A further object is to provide as a simple a solution as possible involving the least possible amount of modification of a previously used design.
The problem is solved according to the invention by providing the differential gear with distribution of torque between a forward driven wheel shaft and a rear driven wheel shaft on a vehicle in which the rear wheel shaft can be raised and the differential gear has an input shaft which via differential pinions is in engagement with a rear differential wheel connected to an output shaft. The input shaft and the rear differential wheel are mutually supported via a bearing which transmits axial forces between them. This bearing is fitted with preloading to eliminate axial play.
Fitting in accordance with the invention a preloaded taper bearing eliminates axial play of the input shaft when the differential is off load. This leads to the input shaft being held in a well-fixed position even when the output shaft is not subject to any torque load.